Download sociosexuality and relationship status interact to predict facial

Human Ethology Bulletin 30 (2015)2: 3-9
Research Article
SOCIOSEXUALITY AND RELATIONSHIP STATUS
INTERACT TO PREDICT FACIAL SYMMETRY
PREFERENCES
Christopher Lustgraaf & Donald F. Sacco
Department of Psychology, Owings-McQuagge Hall, University of Southern Mississippi,
USA
[email protected]
ABSTRACT
Past research demonstrates that the relationship between sociosexual orientation and “good genes”
face preferences is moderated by participants’ own relationship status. Specifically, those women
who are relatively sexually unrestricted demonstrate a greater preference for sexual dimorphism in
faces, but only when unpartnered; for partnered women, sociosexuality does not predict
preferences for sexual dimorphism. The current study extended these findings by assessing whether
sociosexuality and relationship status interact to influence preferences for a different phenotypic
cue, facial symmetry, in both male and female targets. A secondary hypothesis assessed whether
this pattern of face preferences was moderated by either participant or target sex. Men and women
completed a symmetry preference task, the sociosexual orientation inventory, and were asked to
report their relationship status. Unrestricted sociosexual orientation predicted a heightened
preference for facial symmetry in both male and female faces, but only in unpartnered
participants. This effect was not qualified by participant gender. These findings provide
additional evidence that an important moderating variable when assessing the association
between mating personality (i.e., sociosexual orientation) and “good genes” face preferences is an
individual’s own relationship status.
Key words: face perception, evolution, sociosexuality, relationship status
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Lustgraaf, C.J.N. & Sacco, D.F.: Sociosexuality, Relationship Status, and Face Preferences
Human Ethology Bulletin 30 (2015)2: 3-9 INTRODUCTION
In sexually reproducing organisms, including humans, producing healthy offspring is
contingent upon one’s own genetic quality (e.g., mutation load) and that of any partner(s)
one produces offspring with. Given that organisms cannot directly improve their own
genetic quality, it would be adaptive to possess strategies for identifying mating partners of
high genetic quality with whom to mate. Although evolution did not endow organisms with
the ability to detect genetically healthy partners directly, the fact that genes code for
observable phenotypic qualities means that organisms can potentially identify mates of
relatively higher genetic quality through detection of, and preference for, certain physical
cues in faces and bodies (e.g., Rhodes, 2006).
Indeed, a wealth of research has not only demonstrated that individuals perceive certain
physical characteristics as more or less attractive, but also that those preferred traits are
associated with underlying health and disease resistance (Gangestad & Scheyd, 2005). For
example, cross-cultural evidence indicates that people are attracted to individuals with more
bilaterally symmetric faces as well as sexually dimorphic facial characteristics (among other
phenotypic cues). Such differential preferences are adaptive. High facial symmetry is
associated with fewer deleterious genetic mutations and higher levels of disease resistance
(Gangestad, Thornhill, & Yeo, 1994), and more facially symmetric individuals have been
shown to suffer fewer respiratory infections over their lifetime than their less symmetric
counterparts (Thornhill & Gangestad, 2006). In regard to sexual dimorphism, feminization
of female faces is a consequence of exposure to estrogen during development and is
associated with female reproductive value and fecundity, whereas masculinization of male
faces is a consequence of testosterone exposure and has been associated with greater
immune function (Rhodes, 2006; Rhodes, Chan, Zebrowitz, & Simmons, 2003; Smith et al.,
2006).
While such adaptive face preferences have shown remarkable cross-cultural consistency
(see Rhodes, 2006), additional evidence has demonstrated that they are moderated by
individual characteristics, most notably aspects of mating personality and current
relationship status. For example, one of the most common moderators of “good genes” face
preferences is the extent to which individuals adopt a short-term (unrestricted) versus longterm (restricted) mating strategy. When this construct, as measured by the Sociosexual
Orientation Inventory (SOI, SOI-R; Penke & Aspendorf, 2008; Simpson & Gangestad,
1991), is included in research on adaptive face preferences, the results demonstrate that
individuals with a more unrestricted mating personality show stronger preferences for facial
symmetry and sexual dimorphism in faces compared to those with a more restricted mating
personality (e.g., Quist, Watkins, Smith, Little, DeBruine, & Jones, 2012; Sacco, Hugenberg,
& Sefcek, 2009; Waynforth, Delwadia, & Camm, 2005). These results are consistent with
theoretical predictions derived from evolutionary theory in that the short-term mating
strategy adopted by unrestricted individuals leads them to emphasize physical
characteristics related to health and disease-resistance to a greater extent than those with
long-term mating strategies (sexually restricted individuals).
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Lustgraaf, C.J.N. & Sacco, D.F.: Sociosexuality, Relationship Status, and Face Preferences
Human Ethology Bulletin 30 (2015)2: 3-9 Relatedly, recent research has demonstrated that individuals’ current relationship status can
moderate how individual differences in sociosexuality influence preferences for “good
genes” features in faces. Specifically, Sacco and colleagues (2012) measured women’s
sociosexual orientation and their current relationship status, and then asked them to
complete a forced-choice task measuring their preference for sexual dimorphism in faces
(i.e., masculinity in male faces and femininity in female faces). Specifically, participants saw
pairs of male or female faces, with each pair containing a masculinized and feminized version
of a target identity, and were tasked with indicating which face they preferred more. The
results indicated that unrestricted sociosexual orientation was associated with a stronger
preference for sexual dimorphism in male and female faces, but only in women who were
not currently in a committed relationship; for partnered women, there was no relationship
between individual differences in sociosexual orientation and preferences for sexual
dimorphism in faces. Because partnered women’s long-term mating goals have already been
met, such women typically show preferences that are more focused on short-term mating
characteristics such as male masculinity (Little et al., 2002); however, unpartnered women
tend to show more systematic variability in the extent to which their preferences are focused
on characteristics beneficial for short-term versus long term relationships (because longterm mating goals have not yet been met). Thus, it is likely that individual differences should
better tap into variability in mate preferences for unpartnered compared to partnered
women.
Given initial evidence that relationship status and mating personality (sociosexual
orientation) have an interactive effect on preferences for “good genes” cues in faces, the
current study sought to replicate and extend these findings in two ways. Primarily, the
current study assessed preferences for facial symmetry in the context of sociosexual
orientation and relationship status. Considering that previous research investigated
preferences for sexual dimorphism in faces (Sacco et al., 2012), the current study was
designed to test how broadly relationship status and sociosexuality influence preferences for
other “good genes” cues in faces. As a secondary goal, the current study included a sample of
male participants to determine if such findings are specific to female mating strategies or
apply more generally to both men and women; given that men also value cues to genetic
quality and health in faces (e.g., Little, Jones, Feinberg, & Perrett, 2014), it was
hypothesized that participant gender would not moderate the relationship between
sociosexual orientation, relationship status, and preferences for facial symmetry.
In order to test these predictions, men and women completed a forced-choice preference
task that assessed their preference for symmetry in men’s and women’s faces, and then
completed questionnaires assessing sociosexual orientation and current relationship status.
We predicted that more sexually unrestricted participants would show a stronger preference
for symmetry in men’s and women’s faces, but only in unpartnered participants; for
partnered participants, we did not expect sociosexuality to be related to facial symmetry
preferences. Moreover, we did not expect participant gender or target sex to moderate these
findings.
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Lustgraaf, C.J.N. & Sacco, D.F.: Sociosexuality, Relationship Status, and Face Preferences
Human Ethology Bulletin 30 (2015)2: 3-9 METHODS
A sample of eighty-nine undergraduate participants reported to an experimental laboratory
for a study on personality and face preferences. Participants volunteered to complete the
study for partial course credit and signed up to participate via the psychology department’s
research participation recruitment system (SONA). One male participant’s symmetry
preference data was not recorded due to a computer error. Because this study was interested
in understanding heterosexual mating preferences, an additional eight participants’ data
(seven women, 1 man) were excluded from analysis. This resulted in a final sample of 80
participants (13 single men, 28 single women; 8 partnered men, 31 partnered women).
After obtaining informed consent, participants were instructed that they would complete a
face preference task in which they would see pairs of male and female faces and would be
asked to indicate which face they preferred more. During this task, participants were
randomly presented with 20 counterbalanced face pairs (10 male pairs and 10 female pairs).
Each pair consisted of one target facial identity, manipulated such that one version was high
in facial symmetry while the other was low in facial symmetry (stimulus set borrowed from
Quist et al., 2012). On each trial, participants were instructed to indicate which of the two
faces they preferred (similar to past research, we chose to ask individuals to indicate
preference in a non-sexual format so that participants could rate same and opposite sex
faces; Young, Sacco, & Hugenberg, 2011). Following the symmetry preference task,
participants completed the Sociosexual Orientation Inventory Revised (SOI-R; Penke &
Aspendorf, 2008) and a brief demographic questionnaire which included a question about
their current relationship status (as well as their sexual orientation). Participants were
thanked for their participation and debriefed.
RESULTS
To test our primary hypothesis, we calculated preferences for symmetric male and female
faces separately by dividing the number of times participants chose the symmetric target by
the total number of trials for male and female faces, respectively. As the sociosexual
orientation inventory consists of three subscales (behavior, attitudes, and desire), we
computed an average SOI score for each participant (see Sacco et al., 2012 for similar
treatment of SOI data). To test our primary and secondary hypotheses, we conducted a 2
participant sex (male, female) x 2 relationship status (partnered, unpartnered) x 2 symmetry
target sex (male, female) custom mixed model ANOVA, with repeated measures over the
last factor, and included participant SOI and age as covariates (as our hypotheses were
about mating preferences, we thought it prudent to control for any impact of age). There
was a main effect of relationship status, F(1,71)=4.08, p=.047, ηp2=.054, such that partnered
individuals (M=.90, SD=.12) indicated stronger symmetry preferences than unpartnered
individuals (M=.88, SD=.13), which is consistent with past research demonstrating that
people in relationships tend to have preferences focused more on short-term mating
characteristics (Little et al., 2002).
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Lustgraaf, C.J.N. & Sacco, D.F.: Sociosexuality, Relationship Status, and Face Preferences
Human Ethology Bulletin 30 (2015)2: 3-9 Importantly, the only other significant effect to emerge was the critical interaction between
sociosexual orientation and relationship status in predicting facial symmetry preferences,
F(1,71)=4.16, p=.045, ηp2=.055. Because this interaction was not qualified by participant
sex, F(1,71)=1.37, p=.25, ηp2=.019, we tested the correlation between sociosexual
orientation and symmetry preferences separately for unpartnered and partnered
participants. For unpartnered participants, there was a marginally significant positive
correlation between sociosexuality and symmetry preferences, r(39)=.298, p=.059, such
that single participants with a more unrestricted sociosexual orientation indicated a stronger
preference for symmetry in male and female faces. For partnered participants, however, the
relationship between sociosexuality and symmetry preferences was nonsignificant, r(37)=.075, p=.652.
DISCUSSION
While past research has explored the kinds of phenotypic cues that individuals prefer in
others’ faces that connote underlying genetic quality and health (see Rhodes, 2006 for a
review), as well as how such preferences may be influenced by mating personality (i.e.,
sociosexuality) and relationship status (e.g., Sacco et al., 2012), the current results extend
these findings in several important ways. Foremost, past research exploring how
sociosexuality and relationship status interact to influence “good genes” face preferences
examined one cue specifically: preferences for sexual dimorphism in faces. However,
numerous other facial features connote genetic viability and convergent evidence across
different facial feature preferences is necessary to determine how broadly sociosexuality and
relationship status influence face preferences. Secondly, prior research on this topic explored
how sociosexuality and relationship status interact to influence face preferences for women
only. Because men are also motivated to identify healthy conspecifics, it was also important
to determine if these previous findings are qualified by participant gender.
By including male participants and assessing preferences for facial symmetry, the current
study both replicated and extended the previous literature by demonstrating that
relationship status and sociosexuality interact to influence “good genes” preferences more
broadly. That is, sociosexuality also predicts preferences for symmetry in faces for
unpartnered individuals, but not partnered individuals. Furthermore, this relationship
between sociosexuality and face preferences does not appear to be moderated by participant
gender.
Although the sample of participants utilized in the current study was relatively small,
particularly our sample of male participants, the data were collected in a controlled
laboratory setting, thus exerting more control over extraneous variables during data
collection. Furthermore, even with a relatively small sample, our findings are consistent with
both previous literature (Sacco et al., 2012) and with evolutionary theory more generally
(e.g., Gangestad & Scheyd, 2005). Nonetheless, it would be beneficial for future research to
replicate the current findings using a larger sample of male participants. A potentially
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Lustgraaf, C.J.N. & Sacco, D.F.: Sociosexuality, Relationship Status, and Face Preferences
Human Ethology Bulletin 30 (2015)2: 3-9 surprising finding in the current study is the fact that both unpartnered men and women
with a more unrestricted sociosexual orientation demonstrated greater symmetry
preferences for both male and female faces, rather than just opposite sex faces. This finding
suggests that it may be adaptive for heterosexual individuals motivated by a short-term
mating strategy to be sensitive to others who may be a source of reproductive opportunity
(attractive opposite sex targets) as well as individuals who may be a source of intrasexual
threat (attractive same sex targets; see Sacco et al., 2009). Nonetheless, given the now
growing literature on how relationship status moderates the relationship between mating
personality and “good genes” face preferences, it seems prudent for future research to
account for participants’ relationship status when exploring how aspects of mating
personality influence adaptive face preferences.
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